General elections in the Democratic Republic of Congo, originally scheduled for late November, won’t take place until early 2018, the country’s electoral commission said Thursday, risking further violence that could upend the fragile stability of the resource-rich nation.

It is the first time the commission has provided a timeline for when the elections may take place, after saying previously that they won’t happen this year. Critics of President Joseph Kabila say the delay is an attempt to extend his time in power, since...